A rotary tool of the above-described configuration is disclosed, for example, in DE 43 26 793 C1 (U.S. Pat. No. 5,524,315). The subject thereof is to ensure intensive surface treatment and moreover to achieve increased service life.
Notwithstanding this, a polishing tool driven by compressed air is known from EP 0 691 181 B1, which nevertheless is not equipped with a brush holder for an annular brush with a brush strip. Instead, a polishing pad is driven in rotation. Additionally, a cooling air passage is used for injecting air through an air passage in a motor rotary shaft into the central part of the polishing working surface.
Deploying the above-described rotary tools with annular brushes results in a rise in temperature at peak load not only of the bristles and the brush strip but also the tool holder and/or brush holder which generally consist of steel, aluminum or another metal. As a result, the durability, in particular of the rolling brush strip rapidly reduces, so that it may not only lead to premature wear of the bristles but also to premature damage and finally tearing of the brush strip.